I think the 800 mile range is actually driven by re-charge time. If you could get the recharge time down to say 30 minutes to 80, 350-400 miles becomes quite viable. The 800 miles reflects a worst case scenario based on overnight recharging. Many people drive more than 350-400 miles in a day, and requiring a multi-hour stop over to re-charge at the 350 mile point is a deal breaker. However the ability to recharge to 80 in 30 minutes is not a trivial problem. We are probably going to be looking at something in the range of a 100KwH battery pack. That means we need to deliver something north of 160Kw to the charger. That is going to require infrastructure that isn’t located on every street corner, and generally absent in residential neighborhoods. It will also mean putting much higher voltages into ‘public’ places than is common today. It is rare to see anything ‘hotter’ than 3 phase 240v in the USA. 160Kw would require about 230 amps per phase, which is simply not very practical. Just designing a removable connector to deliver that kind of power into the vehicle is going to be challenging. Generally the electric utility gets uncomfortable if you want more than 480 volts on the premises, and as a rule in Electrical Engineering, you try hard to stay below 100 amps because I^2 gets to be very large number very quickly.
IIIRC the pack in most hybrids is on the order of 370 volts, a 100 KwH pack would need a capacity of around 300 amp hours. So to charge in 30 minutes, you would need a charge current of 600 amperes. I^2 is then 360,000 so even a tiny R (.01 ohms) in the connectors translates into a great deal of heat (3.6 Kilowatts of heat)! That means in addition to all the other issues, you would need a reliable way to cool the battery pack during charging, as well as thermal management in the charging process.
One of the advantages of Gasoline is that we can easily transfer large amounts energy very quickly. How long does it take to put 20 gallons/75 liters of Gasoline in the tank? That is about 2.5 million BTU’s. That much energy from electricity is about 73 Kilowatt hours. From a 240V/30 amp outlet that would take 10 hours to deliver! Your typical refueling plaza on can refuel about 60 vehicles per hour, and could deliver about 150 million BTU’s. that translates into 4400 kilowatt hours to be delivered each hour.
My point is the challenges in producing a viable electric vehicle for large scale use go far beyond improvements in battery technology. There is a vast amount of infrastructure that would have to be built to provide. If you want to be able to recharge 60 cars in 30 minutes, you are going to need to deliver 8.8 megawatts. That is a lot of energy, and far exceeds what is available from the light pole in your neighborhood. The costs of providing that kind of power to the refueling plaza’s or gas station on/near Interstate highways are going to be considerable, Given the enthusiasm that most people have these days for Power Transmission lines in their neighborhood or near schools., the problems only get worse.
I have to concede however that electric vehicle use is increasing. I volunteer at local hospital, and our parking garage now has several spots reserved for electric vehicles and we provide a charger at each space. When those spots were created 2 years ago, they were almost never in use. Now most of them are in use in ever day. I am sure that even a few hours of charging is quite useful to the owners of those vehicles.
My other comment is the Green part of electric vehicles is we get to choose the kind of pollution we will create, as well as where to locate it. I am not sure we are going to need a lot more generating capacity. A long range electric vehicle would need to charges no more than once per day. If we do that overnight, we will probably make the electric utilities fairly happy, since that is off peak demand, and would increase the utilization of existing equipment during a period when the utilization isn’t especially high. That range also dramatically reduces the need for recharge station away from home/office. If you can reliably get a full day’s use out of the vehicle, the vast majority of charging will be done at home at night, where an 8 hour charging time isn’t really a problem.
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